Patent GB-801815-A (GB)
Title: Improvements in or relating to electric circuit interrupters
IPC: H01H9/38
Filed: 1956-12-05
Abstract: 801,815. Automatic circuit breakers, contact members for switches. WESTINGHOUSE ELECTRIC INTERNATIONAL CO. Dec. 5, 1956 [Dec. 9, 1955], No. 37150/56. Class 38 (5). A high-speed circuit-breaker, particularly for mercury arc rectifier control, has fixed and moving, main and arcing contacts arranged so that the main fixed contact is resilientfy mounted but its mass is such with respect to the bias of the resilient mounting that it moves more slowly than the moving contact on opening. As shown, the fixed arcing contact 25 is bolted to a fixed conductor 31 having side plates 55, 57 supporting a plate 53 on which the main fixed contact 49 can slide. Springs 71 act on the contact end-projections 65, screw stops 80 on which engage the plate 53 and limit contact movement. Pipes 67, 69 circulate cooling fluid through the contact 49 and flexible connectors 84, 86 complete the circuit to a block 88 connected to a terminal 207. The moving arcing contact 87 is mounted on an arm 109 pivoted at 111 on a channel shaped carrier 95 which is pivoted 101 and also carries the main moving contact 89. The arm 109 is biased in an anticlockwise direction by a spring mounted on a bolt 91 having a nut 121 acting as a stop to the arm. The contacts are biased to the off position by a spring 131 acting on a rod 135 connected to the pivot 111. The carrier 95 is electrically connected by strips 123 to a conductor 127 secured to parallel bars 199, 201 passing on either side of armatures 149, 151 to a terminal 203. The breaker is held closed by a holding magnet 147, having coils 197 and poles 195 which are bridged by the. attracted armatures 149, 151 connected to the ends of a bar 153 by links 155. The bar 153 is pivoted at its centre to a link 157 which is connected by a pivot pin 159 to a rod 161 connected at its other end to the pivot 111 on the contact carrier 95. A link 163 is also pivoted on the pin 159 and at 165 on a link 167 having a fixed pivot at 169. Also pivoted at 165 is a link 171 forming a toggle with a member 175 which has a fixed pivot 177. On the flow of excess current in a forward direction the current in the bars 199 causes a flux to be shunted through a diverter 209 around the air gap for the armature 149 to reduce the flux in the armature which is thus released to allow the link 157 and rod 161 to move in the opening direction. If the current flow is reversed the flux produced by the current in the bars 201 in a diverter 211 reduces the flux in the armature 151 which is released to allow the breaker to open. During the opening movement the toggle 171, 175 collapses and the released armature 149 or 151 returns into engagement with the poles 195. Closing is effected by a crank 191 pivoted to a slotted link 187 acting on a pin 183 mounted on an extension of the member 175. In an alternative contact arrangement (Fig. 6) the fixed arcing contact 219 is bolted to a fixed bar 217 having U-shaped main contacts 215 embracing its end. Springs 227 are arranged between the contacts 215 and the bar 217. The electrodynamic effect of the parallel currents causes the contacts 215 to grip the bar 217 and retard further the follow-up of the contacts which is limited by engagement of cut-out surfaces 251 with the rear face 253 of the arcing contacts 219. The main moving contact 231 is carried on an arm 233 which has the arcing contact 235 pivoted on it at 237 and biased into engagement with the contact 219 by a spring 241 mounted around a stud 247 carrying a stop nut 249.